Admittedly, it's unlikely that eBooks will ever completely replace paper books, unless it gets to the point that paper is such a precious commodity that such publishing becomes cost-prohibitive. Even so, eBooks offer some enormous advantages in comparison with printed books, especially with respect to the type of books which don't really require full-color printing.
In particular, a compact eBook reader such as the new Amazon Kindle 2 can enable one to carry a huge library wherever one goes, without straining one's back (and at a cost which can be much lower than the cost of buying the equivalent number of printed books. The Amazon web site says that the unit "holds over 1,500 books".
Just as an iPod enables people to carry audio libraries which previously would have occupied enough LP records to cause serious back strain when carrying them around (even without the requisite record player), the Kindle 2 does the same thing for books.
PDF formatting can be a good way to create eBooks which are intended for normal computer screens, but smaller machines such as the Kindle 2 really require their own formatting which enables text to wrap properly without the need for horizontal scrolling while reading. Here's a link to one company which can convert various formats such as PDF, Microsoft Word, etc. to Kindle format. (Fortunately, that isn't necessary for PDF files with the new Kindle DX. See notes at the end of this post for more information.)
While Kindle format is clearly best for text, in order to gain the benefits of that format in terms of searching for specific text and so forth, note that the machine also supports a wide variety of other formats "through conversion".
One situation in which eBooks are definitely superior to printed books is for books which must be updated quite frequently, in a manner which does not contribute unduly to the proliferation of discarded outdated printed copies in our nation's dumpsters and landfills. For instance, professional directories (in which the contact information and other details pertaining to companies and individuals listed therein are in a constant state of flux) are a great candidate for eBook publication. It's much easier (and more eco-friendly) to simply upload a revised copy to the web site and to make that file available for download than it is to publish new printed editions of such books.
Kindle isn't just for commercial eBooks, either. Here's a quote which is pertinent to personal documents:
Kindle makes it easy to take your personal documents with you, eliminating the need to print. Each Kindle has a unique and customizable e-mail address. You can set your unique email address on your Manage Your Kindle page. This allows you and your approved contacts to e-mail Word, PDF documents, and pictures wirelessly to your Kindle for a small per document fee--currently only 10¢ per document. Kindle supports wireless delivery of unprotected Microsoft Word, PDF, HTML, TXT, JPEG, GIF, PNG, BMP, PRC and MOBI files.Imagine how useful the Kindle 2 would be to travelers (such as missionaries or band members on the road) who would like to be able to carry their entire libraries with them in order to alleviate boredom or in order to have ready access to far more written materials than they could normally carry with them.
You can email your PDFs wirelessly to your Kindle. Due to PDF's fixed layout format, some complex PDF files may not format correctly on your Kindle.
If you are not in a wireless area or would like to avoid the fee, you can send attachments to "name"@free.kindle.com to be converted and e-mailed to your computer at the e-mail address associated with your Amazon.com account login. You can then transfer the document to your Kindle using your USB connection. For example, if your Kindle email address is Jay@Kindle.com, send your attachments to Jay@free.kindle.com.
Imagine how useful the Kindle 2 would be to students, as an alternative to heavy, back-breaking textbooks.
Imagine how useful the text-to-speech capabilities would be for sight-impaired readers! Ditto for the ability to listen to audio books (MP3) from Audible.com and elsewhere. (For instance, ChristianAudio.com specializes in Christian audio books.)
UPDATE AS OF 5/10/2009: I just learned about a new product in Amazon's line of Kindle readers. It's called the Kindle DX. It's larger than the regular Kindle 2, at 10.4" x 7.2" x 0.38" (versus 8" x 5.3" x 0.36" for the Kindle 2), but the benefit is huge if one wishes to read native PDF files without having to do any scrolling, panning, zooming or reflowing, and without having to convert from PDF format to Kindle format.
The "auto-rotating screen" is also a cool feature, for viewing full-width maps, graphs, tables and Web pages.
Also, Kindle DX has 3.3GB of storage available for user content, which means that it can store about 3,500 books, newspapers, magazines and documents (more than twice as much data as the Kindle 2). Pretty amazing when you consider that it's about the size of a typical magazine.
Personally, though, I think that they should offer a version which has storage via a built-in slot for SDHC cards, which now go as high as 32GB. (Even Micro SD cards can store up to 16GB, based on some ads I've seen.) Oh, well. Nothing's perfect.
I'm inclined to think that it would be particularly beneficial for high schools and colleges to offer all (or at least most) of their text books in the form of Kindle files or PDF files which could be read on the Kindle 2 or Kindle DX. I remember when I was in school, lugging tons of books back and forth between classes. What a pain that was! Kindle DX would solve that problem, with the possible exception of books which were loaded with full-color illustrations which would suffer when converted to a monochromatic display.
It might be nice if other companies would come out with third-party accessories, such as a product which would let one mount the Kindle DX on the wall. (That could come in handy, for instance, if one was using the device to display one's cook book while cooking.) Or a device which would let one mount the Kindle DX on a camera tripod (for prolonged sessions of hands-free reading in areas where there are no desks or tables).